Quite interestingly, most candidates as regular black holes appearing in the literature
(for an incomplete list, see Refs. [1]}) also display a inner horizon.
One might then wonder if trading the central singularity for a Cauchy horizon represents
a real progress in our understanding of black hole physics.
More generally, one would like to understand how regular the geometry really needs to be
for physical consistency and whether this trade-off can be avoided.
